Method of manufacturing plate condensers having discharge elements



y 1969 SHOICHI IWAYA ETAL 3,456,314

METHOD OF MANUFACTURING PLATE CONDENSERS HAVING DISCHARGE ELEMENTSOriginal Filed Dec. 27, 1966 I NVENTORS Shoi. hi, IWVIL BY Tunehikoash/aka United States Patent U.S. Cl. 29-25.42 Claims ABSTRACT OF THEDISCLOSURE A method of manufacturing condensers having dischargeelements which includes forming a conductor into a U-shaped element witha dielectric material such as porcelain between the arms of said elementand dipping the curved portion of the U-shaped conductor and at least aportion of the dielectric material into a bath of hardenable insulatingmaterial such as a thermosetting resinous material for a variable butpredetermined distance so as to thoroughly coat the portions immersedand cement them together. After the resinous material is hardened, thecurved portion of the U-shaped element and resinous material adheringthereto is cut off to divide the conductor into two separate electrodeshaving exposed end portions separated laterally by the dielectricmaterial.

The present application is a continuation of application Ser. No.604,859 filed Dec. 27, 1966.

This invention relates to a method of manufacturing plate condensershaving discharge elements as disclosed in US. application Ser. No.604,859 filed on Dec. 27, 1966, by present applicants, the presentapplication being a continuation thereof and its manufacturing methods.

In a conventional condenser having a discharging gap, a part of eachcondenser electrode itself formed thinly on the dielectric of thecondenser has been used as discharging element. For example, silverelectrodes have been formed in the end part of element of a cylindricalcondenser so that, when an abnormal voltage is impressed there, adischarge may be made and thereby a characteristic of recovery may besoon obtained after the discharge. However, in such condenser, if adischarge is repeated, the thin silver electrodes near the dischargingparts will be destroyed by the discharge and will be apt to be deformedand the flashover voltage will fluctuate, so much as to be higher thanafter 800 discharges. Thus it is difficult to obtain a uniform qualityof discharge element and the life of the condenser is short. It has beendesired to solve these defects as early as possible.

The present invention is an improvement of a conventional condenser.

An object of the present invention is to form a stable discharging partin a plate condenser having a discharging gap.

The present invention relates to a method of manufacturing a structurecomprising a dielectric of a plate shape, a pair of conductors of a bandshape arranged above and below said dielectric in a close and flatcontact with respective surfaces of the latter so as to be a pair ofelectrodes, and an insulating material layer surrounding the dielectricand electrode portions of the conductors so as to hold them integrally.

FIG. l(A) is an elevation of a plate condenser having dischargingelements according to the present invention.

FIG. 1(B) is a side view of the same.

FIGS. 2(A) and 2(B) are views for explaining a method See ofmanufacturing a plate condenser of the present invention.

FIG. 3 is a view showing the present invention as used.

A plate condenser having discharging elements embodying the presentinvention shall be explained in the following. In FIGS. 1(A) and 1(B)showing a plate condenser having discharging elements according to thepresent invention, 1 is a dielectric element made preferably of aporcelain. Such porcelain had better be strongly sintered at a hightemperature and is preferably of titanium or rutile, barium titanate orany alkaline-earth titanate, alumina, forsterite or steatite. Further,the porcelain element 1 should preferably be smooth on the surface andmay be painted on the surface with an ordinary glaze. A band conductor 3is formed in the form of a U on said element 1 as shown in FIG. 2 so asto hold the dielectric 1. After the conductor 3 having extensions 3a and3b at both its ends is inserted into cut groves 16 in a jig 12 so as tobe fitted to the jig, the element 1 held with the conductor 3 is dippedinto a bath of insulating paint 2 contained in a vessel 13. Here 7 is alimiter for regulating the length to be painted in the longitudinaldirection of the element 1. Bolts 8 are screwed into said limiter so asto adjust the position of the limiter.

When heated, the paint 2 deposited on the element 1 of the condenserwill strongly hold the conductor 3 and element 1 and conductor 3 will bestrongly closed each other. The paint 2 is preferably of a material tobe solidified by heat as a vehicle. For example, if a mixedthermosetting epoxy-phenol resin containing a hardener is used, theconductor 3 will be able to be closed against the element 1 at a lowheating temperature. The conductor 3 is made preferably of silverplatedcopper but may be made of a brass, aluminum or iron sheet. The enlargedsurface parts 5 of the band conductors 3 holding the dielectric element1 between them serve as the electrode parts of a condenser. The widthand shape of the conductor parts 5 are selected in response to therequired electrostatic capacitance. Further, the paint part 10 and theconductor 11 at the end adjacent the closed end of the U are cutoff witha diamond cutter 9 or the like along the line a-b. As the element 1forms a part of the cross-section 4 excepting the painting part 10, saidcross-section 4 which is removed the painting part 10 and conductor part11 construct discharging electrodes having a stable dischargingfunction.

Further, a part 15 not painted will be made on said element 1 by thelimiter 7. The reason for its necessity is shown in the following. Aplate condenser having discharging elements according to the presentinvention as used is shown in FIG. 3. The leading parts 13 and 14 of theconductor 3 are used as bent in a direction substantially at rightangles to the dielectric element. In such case, the unpainted part 15will have an advantage of increasing the insulating effect between theleading parts 13 and 14. The generation of coronas will be little.

As the discharging gap is determined by the thickness of the element 1,the discharging elements of the present invention can be formed to behigh in the precision. Therefore, the flashover voltage is very uniformand can be varied by varying the thickness of the element 1.

Though one element is fitted to the jig in the embodiment of thismanufacturing method, it is easy to work many at the same time. It isalso easy to make a complex circuit part. Thus two or more dischargingelements can be formed in the same element 1. In the present invention,it is not necessary to specifically silverplate the element 1.

The conductor 3 should be so smooth as to be easy to bring into closecontact with the element 1. The shape of the conductor part 11 in theend part of the U-shaped 3 conductor 3 should conform to the thicknessof the element 1.

Further, in the present invention, when the electrostatic capacitance ofthe condenser is of a large value, it will not be necessary to make thewidth of the conductor 3 large. The same silver electrode as in theconventional condenser technique may be formed in the element 1 and maybe electrically connected with the conductor 3. As the conductor 3 is inthe form of a flat plate, the radiation of heat is easy.

In such construction as in the above, when a forsterite porcelain plateof a longitudinal length of mm., a lateral length of 7 mm. and athicknesse of 0.5 mm. was used for the element 1 and a copper plate of awidth of 2.5 mm. and a thickness of 0.2 mm was used for the conductor, afiashover voltage of 1500 v. DC was obtained.

Further, even when 5000 discharges were made, the rise of the flashovervoltage was less than 10%. Substantially no variation of theelectrostatic capacitance of the condenser was seen.

Though the discharge generated a corona once, it was soon converted to aspark discharge. The generation of coronas was very little. Even if heatwas generated by a corona loss, the heat was seen to be dissipated intothe atmosphere through the conductor 3.

Further, at not only impulse produced by a fault within the circuit butalso a high voltage close to a direct current, an alternating currentand a high frequency, a spark discharge will be easily generated and thedelay of the spark will be so little as to be presumed to be less than1O- seconds. The voltage-time curve V-t is sub stantially horizontal.Thus the electronic devices can be well protected.

The effects obtained by the plate condenser having the dischargingelements of the present invention as described above can endure manydischarges and give stable electronic circuits. Said condenser is veryeasy to make and can protect electronic devices while keeping the actionof a condenser. Further, in the present invention, the flashover voltageis stable, complex parts can be easily made, the condenser can be madesmall and, as the conductor 3 can be made parallel in packing andtransportation, it is easy to handle. Thus, the condenser of the presentinvention has a technical substance far more advanced than anyconventional condenser and its industrial value is large.

While there has been described in connection with the preferredembodiment of this invention, it will be obvious to those skilled in theart that various changes and modifications may be made therein withoutdeparting from the invention, and it is aimed, therefore, to cover inthe appended claims all such changes and modifications as fall withinthe true spirit and scope of the invention.

What is claimed is:

1. A method of manufacturing condensers having discharge elementscomprising placing a dielectric material having opposed surfaces insubstantially parallel planes between the substantially parallel armportions of a U- shaped conductor near the curved portion thereof,covering the curved portion of said conductor and a portion of thesubstantially parallel arms adjacent said curved portion and at least aportion of the dielectric material disposed therebetween with a liquidinsulating material capable of being hardened, hardening said insulatingmaterial and removing the curved portion of said conductor to expose theends of said substantially parallel arm portions adjacent the end ofsaid dielectric material to form electrodes.

2. A method as claimed in claim 1, wherein the insulating materialcomprises a thermosetting resin.

3. A method as claimed in claim 1 wherein the covering of the curvedportion of said conductor and a portion of the substantially parallelarms adjacent said curved portion and a portion of the dielectricmaterial disposed therebetween consists in dipping the portions into abath of liquid hardenable insulating material for a predeterminedadjustable distance to control the proportion of the dielectric materialand conductor to be covered.

4. A method as claimed in claim 1 wherein the covering of liquidhardenable insulating material will produce, when hardened, a bond toanchor the electrodes securely in close permanent contact with thedielectric material therebetween.

5. A method as claimed in claim 3 wherein that portion of the dielectricmaterial disposed away from the curved portion of the conductor, beforeit is removed, is not covered by the liquid hardenable insulatingmaterial.

References Cited UNITED STATES PATENTS 1/1964 De Gier. 4/1967 Weiss2925.42

